Yarmouth suspension bridge
Yarmouth suspension bridge spanned the River Bure at Great Yarmouth, Norfolk from 1829 until its collapse in 1845. The bridge was widened in 1832, which had not been anticipated by the original design. On 2 May 1845 the bridge collapsed under load from a crowd who had gathered to watch a circus stunt on the river. Some 79 people, mainly children, were killed. An investigation found fault with the design and workmanship of the bridge. The site of the disaster is marked by a modern-day memorial.
Bridge
An act of parliament was passed in 1827 for the construction of a bridge over the River Bure at Great Yarmouth. The Cory family paid for the bridge which was to replace a ferry and provide easier access from the town to marshland, the Vauxhall Pleasure Gardens and a bowling green owned by the family. The investment would be recouped by a toll on those crossing. The architect for the bridge was Joseph John Scoles of London. He designed a suspension bridge with two towers and a clear span of. The span was later increased on site to and the suspension chains increased in length accordingly but it is not thought that Scoles was consulted on this matter.The bridge was supported by a suspension chain at both edges of the deck, each chain being formed from two sets of eyebars which had been made by a local blacksmith. The wide deck, which was slightly arched, carried a central single carriageway of width and two footways each in width. The deck was attached to the suspension chains by vertical iron rods. The towers were constructed on piled foundations on either bank and were apart measured centre to centre. The bridge was constructed by Gidney Goddard and supervised by Mr Green, a local surveyor.
The bridge opened for public use on 23 April 1829. Scoles attended the opening, which was the first time he had attended the site. In 1832 the road from Yarmouth to Acle was routed over the bridge. This had not originally been intended and, to provide sufficient width for two carriages to pass each other, the bridge was widened by hanging the footways from the sides of the deck.
Disaster of 2 May 1845
Cooke's Circus was in Great Yarmouth and as part of a promotion it was advertised that a clown, named Arthur Nelson, would sail up the River Bure in a washtub pulled by four geese on 2 May 1845. The trick, first devised by Dicky Usher in 1809, was achieved by having the tub attached to a rowboat by an underwater line. A large crowd assembled in the vicinity from around 5 pm to view the feat which started with the flood tide. Several thousand people viewed the clown from the river banks and at least 300 in a crowd 4–5 deep on the southern footway of the bridge.At this time one of the eyebars in the southern suspension chain failed; this was witnessed by members of the crowd but no action seems to have been taken to evacuate the bridge as a result. The second eyebar in that portion of the chain took up the full load for around five minutes before it too failed. The south side of the deck fell into the river, though the north end remained suspended by the surviving chain, and the majority of the crowd were tipped into the water. Children, who formed much of the front rank of the crowd, were crushed against the parapet railing by those behind them. One child was saved from being swept away by her mother holding onto her with her teeth.
Boats soon arrived on the scene to rescue the victims. The wounded and dead were taken to nearby houses and pubs. The Union House hotel supplied blankets for the wounded and Lacons Brewery made quantities of hot water available for hot baths to revive the survivors. Some 75 bodies were recovered on the day of the accident, though some remained trapped in the wreckage of the bridge – one man was rescued alive some time later after being freed with the use of a crowbar. In all 79 people were killed in the disaster, of whom 59 were children. Most of the dead were under 13 years of age and the youngest victim was two years old.
Investigation
The coroner's inquest was held the next day in a local church hall. The British government commissioned a report by James Walker, past-president of the Institution of Civil Engineers. Walker found that Scoles' original specification correctly called for high quality iron to be used for the eyebars but failed to specify any testing of the product. He found that the failure occurred in a joint within the eyebars – each of which had been forged from three separate pieces: two eyes and a bar. The scarf joint between the components had been imperfectly welded with the weld covering only one third of the surface area of the joint. Had the welds been carried out correctly it is likely that the rods would not have failed. Walker also noted that the rod portion of the eyebars was made of better quality iron than the eyes and that the second rod to fail had extended by around an inch under the load imposed.There was further discussion of the report by several leading engineers in the Proceedings of the Institution of Civil Engineers. Walker claimed that the decision taken to widen the bridge was a poor one. Though the additional weight imposed was small compared to the weight of the original deck the extra weight, being outside of the original deck area, was carried entirely by one of the chains. It was thought that, had the bridge not been widened, it would have been able to accept the crowd loading. Indeed crowds of 2–3 times as many people had previously been present on the bridge but the loads had been spread more evenly across the two suspension chains.
Leading bridge engineer and future ICE president James Meadows Rendel was of the opinion that such a slender suspension bridge should not have been constructed in a location susceptible to crowd loading. He noted that a similar bridge at Montrose, Angus had collapsed when a crowd formed on it to observe a boat race. Rendel described the Yarmouth bridge as "a mere toy" and that the design was not well conceived. He was of the opinion that a traditional arch bridge should have been constructed instead or otherwise the deck made rigid by use of a truss.
The primary cause of failure was attributed to the welding of the eyebars which was described as defective. Rendel found them to be of such poor quality that they would have failed under any adequate scheme of testing. Regular maintenance inspections of the bridge may have picked up the issue and one ICE member made the recommendation that public bridges be regularly inspected by a competent engineer.